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Troubleshoot a Slow Computer Network – Your Computer is Slow and Not the Network

Slow Data Transfer is not Always caused by the Network

Slow data transfers are sometimes caused by a slow computer. Determine if the computer is the reason by comparing the transfer speed with a different computer connected on the same switch port. If the speed is the same, the problem is your network. If you get faster data transfers with a different computer then the problem is the computer.

A computer could be slow because of various reasons:

A bad network card. Troubleshoot: Swap the network card and test the data transfers afterwards.
The computer is outdated and it runs software that needs more resources. Troubleshoot: change the computer.
Slow hard-drive. The hard-drive will always be the computer’s bottle neck. It is the slowest part of a desktop computer. Old hard-disks are very often seen in new computers. Hard-disk fragmentation is a frequent reason for slow computers. Troubleshoot: Defragment often your hard-drive and reserve a 25% free space on the drive.
The computer might be infected with a virus or a Trojan. Troubleshoot: scan the computer for viruses. On a Windows machine run the command “netstat -a -b” to see what ports are being used and which program is using them. Use a network sniffer and monitor the network activity on the specific computer.
The transfer is intermittently slow, check what background processes are using the CPU, Memory, and hard-drives. Windows Vista can sometimes be a resources hog by allocating too many resources for background processes such as indexing and running the antispyware. Antivirus or other antimalware can consume a lot of the computers’ resources. Troubleshoot: Change the schedule for maintenance tasks to a time when you are not using the computer. Check what other programs are running in the background and configure accordingly. Some antivirus programs enable scanning the network drives by default.
A slow network printer. A slow network printer can be caused by the power save feature. If you use the printer very often you might consider turning off the power save.
A slow Network Attached Storage device. A slow NAS could be caused by improper SAMBA configuration or a disk power save feature. The power save feature is fairly easy to fix, just disable it if you find that you are using the drive very often. The SAMBA tune up is more difficult and usually it is complicated to have terminal access to the device itself. Many manufacturers do not allow direct access to the OS. SAMBA is a free implementation of Microsoft’s SMB protocol. SAMBA, SMB and CIFS offer file and print sharing services for Windows and Linux/Unix machines

This article is part of a five posts series regarding Network Troubleshooting.

The Domain Name Scam Explained

Domain Name

Protect your Domain Name?

If you are a Domain Name owner and make business on Internet you know that your Domain Name is one of your biggest assets.

You wouldn’t give away any traffic resulted in misspelling of your domain name or traffic generated by similar domain names.
There are actually people on Internet who specialize in stealing traffic from other companies. They do this by using domain names similar to successful companies. However this is less feasible these days because domain name doesn’t carry too much weight in SEO.
If someone would try to register your domain name, what would be your reaction? Your first reaction, of course, would be to protect your domain name. You want to buy that domain so nobody else could use it and steal your traffic. This is a natural reaction; you are trying to protect your asset.
This weakness is exploited by a large number of companies, (mostly Chinese), specialized in this type of scam.
There is nothing wrong to secure that domain name, if you think it makes sense for your business, many companies do this, just don’t buy the domain name from the spammers. Buy that domain from a reputable registrar instead.

How does the Domain Name Scam work?

The spammer collects information from the Domain Name registration which is, in most of the cases, public. This information contains the owner name, the email address, and of course the Domain Name. This information is enough to devise an email which will be sent to the CEO. The email informs the owner that another company is trying to register the domain name in cause but for another TLD or ccTLD.
As the owner of the domain you “get the benefit of being announced of this purchase” and are being offered to buy it yourself.

For instance you own domain.com and someone is trying to register domain.tw and domain.cn, etc… Other country-specific flavors (.asia, .biz, .cc, .cn, .com. cn., .hk, etc.) can be mentioned. You are informed about this and offered to buy the domain or the domains.

Scenarios when Contacted by a Domain Name Scammer

At this point there are a few possible scenarios:

First scenario: You don’t really need the domain names but you fall for the scam and say “yes, please register all of these domains for me”.
This is the worst case. These types of companies are ghost companies that charge you three to ten times the regular price of the domain. Sometimes, if you don’t pay attention to all the registration details the scammers will register themselves as registrant and administrative contacts and they will keep themselves in the loop trying to reap you off more down the road.
Second scenario: You look at the domain names list they sent you, you pick the ones you are interested to protect and register them at a serious registrar for a fair price. See this post about Protecting the Trademark by Registering Domain Names. You might have a Web Marketing strategy that involves buying those domain names. In this case the scammers made you a favor reminding you to buy some domains that you missed.
Third scenario: You simply ignore the email; you don’t care if someone registers the domain domain.cn, these days a domain name doesn’t count that much for the traffic as it used to. The content is king and traffic leaking is almost impossible only using a domain name. Protecting your Trademark is your lawyer’s job and there is no need to buy everything on the market to protect your Trademark. See this article about the defensive domain buying: Protecting your Trademark by buying as many as possible domain names.

The decision is not always simple and it depends on your business needs. You could go with either the second or the third scenario.
You can Buy International Domain Names at fair prices at: Go Daddy Bulk Domain Registration

Regardless of your business needs you will probably want to avoid buying these domains from the scammers.

Please improve this post by commenting.

How to – Debian Static IP Configuration

On a basic Debian machine without a graphical interface assigning the same IP address all the times can be achieved in two ways.

Static IP Address

To configure a static IP, (an IP that will never change), and not use DHCP you must edit the file /etc/networking/interfaces.
Insert the following code at the end of the file and don’t change anything else unless you know what you do:

# The first network card – this entry was created during the Debian installation
# (network, broadcast and gateway are optional)
#Private Interface
iface eth0 inet static
address 192.168.0.254
netmask 255.255.255.0
network 192.168.0.0
broadcast 192.168.0.255
## only use gateway if your machine is not multi-homed, (two network cards). You can only have a default route.
# gateway 192.168.0.1

In our case the IP of the Debian machine is 192.168.0.254. The gateway, (the router), is 192.168.0.1 and it is a standard Class C network.

To refresh the network configuration without restarting the server execute:
/etc/init.d/networking restart

If that doesn’t work reboot the machine (reboot or init 6).

For a second network card you should add at the end of the file another entry for your second card:
#External interface
iface eth1 inet static
address 1.1.2.2
netmask 255.255.255.0
network 1.1.2.0
gateway 1.1.2.254

Check the new configuration by issuing the command:
ifconfig

DHCP Reserved address

If you want to set this via DHCP you have to make a reservation into your DHCP server for your network card’s MAC address.
You can find your MAC address by using the command ifconfig.
The server will spit some information on the screen that looks like this:
eth0 Link encap:Ethernet HWaddr 00:33:ff:c4:2f:2b
inet addr:192.168.0.254 Bcast:192.168.10.255 Mask:255.255.255.0
inet6 addr: fe80::230:f4ff:fdd4:bf33/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:93373 errors:0 dropped:0 overruns:0 frame:0
TX packets:38320 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:76539317 (72.9 MiB) TX bytes:5551726 (5.2 MiB)
Interrupt:17 Base address:0x6000

The first line is the one you are interested in:
HWaddr 00:33:ff:c4:2f:2b
In your DHCP server make a reservation using 0033ffc42f2b as your MAC address. Note the removal of the colons in between.
Reboot the server and when the machine will try to renegociate its IP address the DHCP server will assign it the newly reserver address.

If you want to add a static route on your Debian machine edit your /etc/networking/interfaces file and add the following two lines at the end of your eth1, (eth0), configuration.
up route add -net 192.168.22.0 netmask 255.255.255.0 gw 192.168.100.254
down route del -net 192.168.22.0 netmask 255.255.255.0 gw 192.168.100.254
The two lines tell Debian to add a static route when the computer boots, and to remove the static route when it shuts down.

The parameters mean: 192.168.22.0 is the network you want to make your Debian machine aware of; 255.255.255.0 is the netmask of your added network, 192.168.100.254 is the gateway to that network.

Why would you need a static network? In our configuration example your default route is through your public network interface.
Any additional internal networks or VPN’s will not be available. The configuration above tells your Debian machine how to reach any VPN or networks not reachable via the default Network.

There is another change needed if you plan to configure this machine as a simple router. You need to enable IP forwarding, in other words allow the machine to forward traffic for its clients.
# nano /etc/sysctl.conf
Change the following line : net.ipv4.ip_forward = 0
to net.ipv4.ip_forward = 1

Reboot the machine to make the setting active, or issue the following command to make the kernel aware of the change:
# echo 1 > /proc/sys/net/ipv4/ip_forward

Why do you want your Debian machine to connect to other networks or VPN’s? If your machine is a proxy, or a gateway it needs to know where to route packets for its clients. Even if your remote networks or VPN’s have their own proxy, if you have a shared server in one of these networks you need to make it available for your users. It is easier to maintain a static route on one server than add it to all of the clients.